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Exploration of Certain Iron-Ore and Coal- 
Deposits in the State of Oaxaca, Mexico. 




BY 

J. L. W. BIRKINBINE, 

\\ 

PHILADELPHIA, PA. 


A Paper Read before the American Institute of Mining 
Engineers, at the Pittsburg Meeting, 

March, 1910. 


> > 
> > > 


AUTHOR’S EDITION. 




1910 . 














































SUBJECT TO REVISION. 


[TRANSACTIONS OF THE AMERICAN INSTITUTE OF MINING ENGINEERS.] 



•» 

Exploration of Certain Iron-Ore and Coal-Deposits in 
the State of Oaxaca, Mexico. 

BY J. L. W. BIRKINBINE, PHILADELPHIA, PA. 

(Pittsburg Meeting, March, 1910.) 

Introduction. 

This paper is a discussion of a part of the mineral wealth of 
the States of Oaxaca and Puebla, Mexico. It does not refer to 
the precious metals, some mines of which, in these States, are 
said to have been worked before the advent of the Spanish 
conquistadores in the sixteenth century, as my purpose is to invite 
attention to the exploration of deposits of coal and iron-ores in 
the Mixteca region. The prominence given to coal is war¬ 
ranted by the great effect of the scarcity of fuel upon the indus¬ 
trial development of Mexico. Under the progressive admin¬ 
istration of President Porfirio Diaz, the Republic has made 
wonderful advances in the past three decades; and this pro¬ 
gress would have been greater hut for the limitations imposed 
by expensive fuel. 

In the spring of 1906 I was detailed by the Birkinbine Engi¬ 
neering Offices, of Philadelphia, to accompany A. B. Adams, of 
Hew York, in a reconnoissance of reported deposits of iron-ores 
in the State of Oaxaca. The result of this expedition was the 
formation, in 1907, of the Oaxaca Iron & Coal Co., of which 
Mr. Adams became, and has remained, President and General 
Manager, and I have spent the past three years as Chief Engineer 
of this company in Mexico, principally in western Oaxaca, 
where field-headquarters were established. 

Geography and Population. 

Although the geographical and topographical features of 
the Republic of Mexico are well known, few realize that the 
majority of its population is domiciled in the States which 
immediately surround the capital city of Mexico, including 
the Federal District, Mexico, Tlaxcala, Morelos, Puebla, 

[i] 




672 EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


Oaxaca, Vera Cruz, Hidalgo, San Luis Potosi, Queretaro, 
Guanajuato, Aguascalientes, Jalisco, Colima, and Michoacan. 
These States cover 177,600 sq. miles of the national total of 
767,300 sq. miles. The census of 1900 gave these 15 States a 
population of more than 9,485,000, out of 13,606,000 for the 
entire Republic. In other words, 23 per cent, of the area of the 
Republic contains 70 per cent, of its population. With the pos¬ 
sible exception of the portion of the State of Yera Cruz adja¬ 
cent to Gulf ports, the present price of coal in this region ranges 
from $7 to $15 a ton, on board cars at railroad termini. 
(The values are given in gold. Mexican currency is taken as 
worth 50 per cent, of gold-value.) Within the region numer¬ 
ous mining and industrial centers are seeking economical 
power; and coal, crude oils, and gas (utilized in gas-engines), 
as well as hydro-electric installations, have received attention 
and encouragement. Mexico City being the center of popula¬ 
tion, industry, and commerce in the Republic, the prices of 
various commodities at that place are given in this paper. The 
metric ton of 2,204.6 lb. av. is used, unless some other unit is 
stated. 


Fuel in Mexico. 


Wood and charcoal, exclusively used as fuel in the past, are 
still largely relied upon, even in important cities; but the rapid 
destruction of forests adjacent to lines of transportation has 
greatly augmented the cost of vegetable fuel throughout the 
Republic, thus encouraging the use of coal, which is now gen¬ 
erally burned under boilers, and has been utilized lately in 
gas-producers, the gas thus generated being supplied to heat¬ 
ing-furnaces and to internal-combustion motors for power. 
Some industries are applying waste charcoal-breeze in special 
producers to operate gas-engines; and numerous locomotives 
are burning crude native petroleum. 

The most densely populated part of Mexico is distant from 
present fuel-supplies. The wood along the railroads entering 
the valley of Mexico has been depleted; and the only domestic 
coal now available is mined more than 800 miles to the north; 
while foreign coal must be transported from Gulf ports, a dis¬ 
tance of 264 miles by minimum haul, overcoming an elevation 
of 8,400 ft. before descending into the valley of Mexico, the 
altitude of which is 7,300 ft., and necessitating a charge of 





EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


673 


$4.75 per ton tor freight between Vera Cruz and Mexico. For¬ 
eign coal, therefore, costs from $10 to $11 per ton in Mexico 
City, and about 25 cents less in Puebla. Anthracite coal from 
the United States and u Crown fuel’’-briquettes, imported from 
Great Britain, command from 50 cents to $1 per ton more than 
bituminous coal. 

In the northern part of Coahuila, extensive coal-deposits 
have been developed, but they are more than 800 miles from 
the City of Mexico, and 6,000 ft. below it in altitude; and the 
railroad freight-charge averages about $4.50 per ton, making 
the domestic coal sell in Mexico City at from $8.50 to $10 per 
ton. The Coahuila coal is high in ash (from 15 to 18 per cent, 
by average analyses of imperfectly-washed coal); indeed, coal 
from this field carrying as much as 25 per cent, of ash has been 
sold in Mexico City. These deposits were described by Edwin 
Ludlow in a paper presented at the Institute meeting in Mexico, 
November, 1901. 1 

Coal has been found also in the State of Sonora, still further 
from Mexico City. These deposits were described by Prof. 
E. T. Dumble 2 before the Institute in 1899. 

Petroleum, which is obtained along the Gulf coast, com¬ 
mands about the same price per ton as Crown fuel-briquettes or 
Pennsylvania anthracite, being handicapped by the same trans¬ 
portation-charges to Mexico City. Lately the wells have been 
damaged by the intrusion of salt water, which, while not inter¬ 
fering with the character of the refined products, affects the 
value of crude oil as fuel, and thus restricts consumption, espe¬ 
cially on the railroads. 

The Mixteca Region. 

Near the central portion of the Republic, between the par¬ 
allels of latitude 15° and 18° 30' north, and between the 
meridians of longitude 20° to 21° 15' west of Washington, 
is the Mixteca region, embracing about the western third of the 

State of Oaxaca and the southwestern portion of the State of 

# 

1 The Coal-Fields of Las Esperanzas, Coahuila, Mexico, Trans., xxxii., 140 to 
156 (1902). 

2 Notes on the Geology of Sonora, Mexico, Trans., xxix., 122 to 152; and 
Natural Coke of the Santa Clara Coal-Field, Sonora, Mexico, Trans., xxix., 546 
to 549 (1899). 

. [ 3 ] 




674 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 



PUEBLA 


uelmetlano? 


Matamorps 


Cliietla 


ntlan 


Tezi: 


Mucio Mi 


Tihuicinj 


Acatlan 


'etlancingo 


r ecoraatlan 


Ch i la 


ta.Anna? 

Rayon 


Hnajuapam 


Tezoatlan 


Tonala' 


Diquillu 

Consuelo 


Teposcolula 


oapam 


Nocliixtla: 


ixtlahui] 


ilateo PenaSeo 


OAXACA 


Caiiuk’cua 


Ziinatlan 


Las Reyeso 


'erreriafflan'Rafial- 


Atoyoquilla'' 


Ejutla o 


Zeniza 


Ja;niltepec o 


SCALE 


KILOMETERS 
1 I-1- 1 - 


MILES 


Tepeaca^j 

t teli if 

'MRosendo Marquez 

NoTecamaelialco 


eeamaclialco LEGEND 

\ _State Boundaries 

\ - Existing Railroads 

\ Proposed Railroads 

\ mmm Coal Fields 

\ HB Iron Ore Deposits - 

jliuacanX @ State Capitals 

o Towns 


Piastla 


Cuieaplan 


El Parian 


1°30 


Fig. 1.—Map of the Mixteca Country, States of Oaxaca and Puebla, 
Mexico, Showing Coal-Basins, Iro^-Ore Deposits, and Existing and 
Proposed Railroads. 


[ 4 ] 






































































EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


675 


Puebla. The country is mountainous, extending from sea- 
level at the Pacific ocean to 10,000 ft. above, the average 
altitude being more than 5,000 feet. 

Its ancient history, like that of many other parts of Mexico, 
is unknown; but numerous ruins and peculiar languages or 
customs, which still prevail, indicate that the original Mixtecas 
had reached a comparatively high plane of civilization. 
According to common legend, supported by the opinion of 
some archaeologists who have lately visited this portion of 
Mexico, the Mixteca Indians antedate the Aztecs, and it is 
possible that they accompanied the Toltecs when these entered 
Mexico from the north. In some parts of Oaxaca there are 
colonies of Indians known as “ triques” believed to have been 
originally communities of prisoners gathered from the numer¬ 
ous campaigns of the Mixtecas against other tribes. What can 
be learned of the history of the Mixtecas indicates that they 
retained their independence until after the arrival of the Span¬ 
iards in 1525; and it is commonly asserted that the Mixtecas 
and the Tlaxcalans were the only two independent tribes that 
withstood the conquest of the war-like Aztecs, to whom even 
their former allies, the Zapotecas, were finally forced to yield. 

The Mixteca region is divided topographically into two parts, 
known as the Mixteca Arriba and the Mixteca Baja; and 
inhabited by separate clans, exhibiting still marked differences 
in language. 

The Mixteca Indian is usually peaceful and industrious, 
and develops, with very little training, into a skilled workman 
with a tendency to be busy before the working-day begins and 
to continue long after hours in order to complete the task once 
begun. He has a happy disposition and works for very small 
wages, so long as he may remain in his own part of the country, 
to which he is strongly attached. Although always craving for 
an opportunity to visit Mexico City, he is just as anxious to 
return to his own land, as soon as he has seen some of the 
modern wonders of the capital. 

In our reconnoissances in the spring of 1906, we were proba¬ 
bly the first American party to make an extended visit to this 
part of Mexico. For weeks at a time we traveled on horse¬ 
back through this unmapped portion of the Republic with 

perfect security, receiving everywhere not only courtesy but 

[5] 


676 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


sincere hospitality. Doubtless many of the attentions we 
received were due to letters and instructions sent by General 
Diaz (who, like the other great executive of Mexico, Benito 
Juarez, was a Oaxacan), and by the present Governor of the 
State, Emilio Pimentel. Yet, even peones , who had no way of 
knowing that we were bearers of official letters, were sponta¬ 
neous in their courtesy and assistance, showing their desire to 
aid us in every way. In three years of nearly continuous resi¬ 
dence among these people, I have found them always courteous, 
reliable, and honest. So much has been published concerning 
the indolence, inefficiency, and dishonesty of the Mexican peon , 
that the above statement, based upon long and intimate asso¬ 
ciation, is offered as an offset to the generally-accepted opinion. 

i 

Labor. 

The Mixteca Indians furnish an ample supply of labor, and, 
with little training, become skilled in the duties assigned to 
them. The following rates of wages prevail throughout the 
work: 

Day-laborers, unskilled, and speaking only the Mixteca dia¬ 
lects, receive from 9 to 12.5 cents per day of from 10 to 12 
hours. 

Day-laborers, unskilled, but speaking Spanish, and also mine- 
muckers, receive 12.5 to 18 cents per day. 

Gang-foremen, blacksmiths, and carpenters, 31 cents per day. 

General foremen and special office- and laboratory-man, 50 
cents a day. 

They appear to be born mechanics, soon learning to tire the 
drill-boilers, to operate the hoisting-engine, and to make, 
out of old pieces of available scrap, any small parts neces¬ 
sary for repairs. They can be trusted, if not too severely 
tempted, and, if treated with kindness and firmness, they are 
extremely loyal. For packing heavy loads they are invaluable 
and indefatigable. Like all other Spanish-American countries, 
Mexico has innumerable feast-days; but hitherto our men have 
been perfectly willing, in cases of necessity, to let these go by. 
Their chief weakness is a love for alcoholic drinks, especially 
aguardiente (which is practically pure alcohol); and their 
favorite time for its consumption is on Sundays and holidays. 


'EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


677 


Surveys. 

The exploratory concession granted to the company em¬ 
braced nearly 11,000 sq. miles, the existing cartography of 
which was either meager or inaccurate. It was therefore 
necessary to survey this area. ] There is a government triangu¬ 
lation-system (known as the triangulation upon the meridian 
98° west of Greenwich) embracing much of this region. The 
stations are from 20 to 70 miles apart, and we were conse¬ 
quently obliged to make a secondary triangulation at essential 
points. Two base-lines were measured, one in the vicinity of 
Tlaxiaco, 1,691.785 m., and the other, 1,126.12 m. long, in the 
vicinity of Tezoatlan. The first, or Tlaxiaco, system of triangu¬ 
lation embraced an area of 860 sq. km. (more than 140 sq. 
miles), with several high peaks at greater distances (located by 
observations from two points). One of the government trian¬ 
gulation-stations formed p&rt of this system. The Tezoatlan 
system included 600 sq. km. (more than 230 sq. miles). From 
the secondary triangulation-stations, third systems were ex¬ 
tended to cover smaller areas, embracing the coal-fields at 
Mixtepec and at Mina Consuelo. In the vicinity of Mina Con- 
suelo and of Tlaxiaco, the meridian was determined, and per¬ 
manent monuments were erected. 

It may be of interest to detail the method of obtaining base¬ 
line measurements, in a country where a satisfactory straight 
line on ground, which was level or had a uniform slope, could 
not be secured, and the system carried out in the triangulation. 
The base-line was determined with a standardized steel-tape, 
100 m. long, supported at intervals of 5 m., measurements being 
taken when the temperatures of the ground and of the air were 
practically uniform, with a strain of 15 lb. on the tape. The 
supporting-stakes were on uniform grade-lines, and each end 
of a grade-line was considered as an intermediate station. The 
difference in elevation between these ends of grade-lines was 
subsequently determined by means of a level. Two sets of 
measurements with the tape and two sets of levels were run 
over the base-line by different observers, and the results were 
calculated. When these checked within 5 mm. the mean was 
adopted as the final measurement. From the ends of the base¬ 
line the triangulation was made with a Gurley light mountain- 
transit, graded to read to 30", the angles being repeated 10 

[7] 


678 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


times, and the total being divided by 10 gave the reading 
within 3". Where any angle or measurement of a series, dif¬ 
fered from the mean by 30" or more, a new series of- readings 
was taken. The light mountain-transit was adopted, although 
having the disadvantage of a small limb, because its ease of 
transportation and stability in adjustment made it superior to 
the larger transits for the use to which it was put. All tran¬ 
sits were equipped with full vertical circles and two with Seg- 
muller solar attachments for determining the meridian at dis¬ 
tant points by observations on the sun; also one with a repeating 
vertical arc, in order that leveling by vertical angles and de¬ 
termination of latitudes could be accurately made. 

In addition to the above-mentioned triangulation-systems, 
400 acres have been covered by accurate topographic survey, 
and sketch-topography covering 1,250 sq. miles has been made. 
Most of this work has been done by Assistant Engineer H. N. 
Roberts, who deserves credit for accuracy, thoroughness, and 
close attention to details. Practically all the concession of 
11,000 sq. miles, as well as several thousand square miles in the 
State of Puebla, has also been reconnoitered on horse-back or 
on foot. 

Equipment. 

As it required from 3 to 5 days for mail to pass from the 
headquarters at Tlaxiaco, and from 5 to 7 days from the field- 
headquarters of Mina Consuelo, to Mexico City, while freight 
and express consumed from 10 to 30 days in transit, it was 
necessary to equip the corps liberally, including a miniature 
field drug-store for accidents or sickness (which, fortunately, 
has been little used in the past three years). Drawing-rooms 
were established at the two above-mentioned points for plotting 
maps and geological data, the designing of head-frames and 
small ventilation-systems for some of the drifts, etc. A field- 
laboratory, first established at Tlaxiaco, but later moved to 
Mina Consuelo, was equipped to make chemical analyses of 
iron-ores and coals, and provided with apparatus for certain 
physical tests, including a Parr calorimeter and a petrographi- 
cal microscope. Several crude pieces of apparatus were con¬ 
structed for experimental tests in sizing or washing coal. Two 
“ C ” Sullivan diamond-drills, with water-tube boilers, pumps r 

drill-rods, core-barrels, casing, stand-pipe, and necessary tools 

[ 8 ] 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


679 


and extra parts, were transported to the field-headquarters by 
mules. Hand-drills, sledges, tools, blacksmith and carpenter 
outfits, portable forges, provisions, and camp-equipment were 
also provided. At Mina Consuelo it was necessary to erect all 
buildings, which at first were of the native style, bamboo tied 
with reatas (i. e., ropes made from palm-leaves) and a roof made 
from the palm; but these were afterwards superseded by a log- 
cabin, in which the logs were held together by pins of wood, 
with split-shingle roof. Dwelling-houses, laborator} r , and dining¬ 
room were built of logs and split shingles, as well as the head- 
frame at the shaft, store-house, stable, and blacksmith-shop. 

Since the only hand-tools available in the field of our explo¬ 
rations were of ancient design (with which, however, the na¬ 
tives did excellent but slow work), the equipment supplied in¬ 
cluded what would be a fair stock for a small hardware-store 
in the United States. 

Our assistants came from the United States, England, and 
Canada, but the packing and other labor was done by a liberal 
force of natives, whose wages, however, did not make the work 
expensive. 

The reconnoitering parties were equipped with horses, sad¬ 
dles, serapes (native blankets), and jwnchos for each member; 
and each party had also an aneroid barometer, a Brunton com¬ 
pass, a Maignen filter, one or two prospecting-picks, medicine 
cases, note-books, and pencils. Exploratory parties were also 
supplied with camp- and cooking-equipment. 

Geology. 

The coal-deposits in the Mixteca region must have been 
known for more than half a century. There is an old drawing, 
bearing the title, Croquis de la Area Carbonifera de Tlaxiaco 
descurbierta por Jose Vincente Comacho en 1850. (Sketch of the 
Tlaxiaco Carboniferous Area discovered by Jose Vincente 
Comacho in 1850), upon which are shown several drifts and 
outcrops; but no work, except a few short drifts scattered over 
a large area, and a trench near Mina Consuelo, had been done 
in the region prior to 1907. 

The first geological study of the Mixteca region, of which 
records can be found, was made by Inginiero Santiago Ramirez, 
who examined, in 1881, some coal-outcrops near the boundary 

[9] 


680 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


between Oaxaca and Puebla. In the same decade, Messrs. 
Felix and Linke made geological studies in the vicinity of 
Tlaxiaco; and in 1887-1888 Sr. Jose G. Aguilera, now 
Director of the Instituto Geologico Nacionale, examined the 
vicinity of Tezoatlan and the northern part of the State of 
Oaxaca. The activity of the Oaxaca Iron & Coal Co. attracted 
to this undeveloped held the interest of the National Geological 
Institute, which, in the fall of 1908, sent an engineer to visit 
the Mixteca region. He collected for the Institute considerable 
geological data and numerous fossils, and examined some coal- 
outcrops, which, however, he regarded as possessing no import¬ 
ance, since he was able to find but few samples that carried less 
than 18 per cent, of ash, which he considered to be amaximum for 
useful coal. In the spring of 1909, the Director himself accom¬ 
panied me in a brief tour of inspection to some of the deposits; 
and somewhat later commissioned another party, composed of 
Prof. G. R. Wieland and Inginiero Bonilla, to visit the Mixteca 
region. They spent several months in the field; but the 
work of these geological parties was directed rather to the cor¬ 
relation of the various strata, to petrograpliical determinations, 
and to the collection of fossils, than to economic geology. 

Geology of Western Oaxaca. 

In the territory under discussion the general geology may be 
described as follows; 

The lowest formation is the Archaic, consisting of gneiss, 
mica-schists, and mica-slates. On this are superposed small 
areas of Jura-Trias, while over larger areas appears the Creta¬ 
ceous formation. The pre-Cretaceous Mesozoic rocks gener¬ 
ally consist of shales (varying greatly in composition), coarse 
and fine sandstones, and conglomerates, also some quartzites. 
The Cretaceous is represented mostly by massive limestone, 
although in some parts slates and calcareous sandstones are 
found. Above the Mesozoic formations occur in some places 
the Tertiary red sandstones and conglomerates, and in other 
places “ caliche ,” which is either of Tertiary or Quartenary 
age. 

i 

Throughout these various formations, although more pre¬ 
dominant near the junction of the Archaic and the upper sedi¬ 
mentary rocks, large areas are covered by Tertiary intrusives 

[ 10 ] 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


681 


SYMBOLS 

y. Coal Outcrops 
Dip and Strike 
Streams 

Triangulation System 
« Towns 



I ? 1 Unidentified Rock 
i—i—i Limestones 


Sand and Lime 
Shales 

~ x-per Coal- 
Bearing Shales 

Sandstones and 
Conglomerates 

Lower Coal- 
Bearing Shales 

53 Schists-Archaic 
• -I Intrusive Rock 




»V 


o* 




SECTION ON LINE A-B 



SCALE 


o Vi 1 


o 


—i—r 

Vi 


—i -r 

2 3 

~i- 

i 


M 


SECTION ON LINE M-N 


* * * 


r * * 




* * " 


V * 


v r * 


*/ * * 






i Km. 


2 Miles 



Fig. 2.—Geological Map and Sections, Vicinity of Mina Consuelo, 

Oaxaca, Mexico. 


[ 11 ] 























































































































































































































682 EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


ui* 



A 


(andesites, basalts, rhyolites, etc.), while in some localities lava- 
flows and masses of obsidian are found. The Mesozoic forma¬ 
tions of the region are extremely interesting to palaeontologists, 
on account of the lar^e number of fossils which they contain. 
The Jura-Triassic carries a great variety of mollusca and plant- 


a 


2 <3 o 

/ 



c 


Fig. 3 (A, B, C, D).—Geological Section, Vicinity of Mina Consuelo, 

Bore-Holes 


[ 12 ] 









EXPLORATION OF IRON-ORE AND COAL-DEPOSITS 


683 





B 


forms. The mollusca include several forms of trigonia and 
stefonigero ; while among the plant-forms cycads are predomi¬ 
nant, although there is beyond doubt a great variety of other 
forms. Professor Wieland, in his paper entitled The William- 
sonias of the Mixteca Alta, says: “I am of the opinion that 



D 


Oaxaca, Mexico, at Bight Angles to the Strike-Line and through 
Nos. 3 and 4. 

[13] 


0 














684 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


the Mixteca Alta is one of the most promising and accessible 
regions for the student of fossil plants yet discovered/’ 3 

The various formations of the pre-Cretaceous Mesozoic have 
not been correlated, being grouped under a general term as 
Jura-Trias; but the thick Cretaceous limestone is sufficient as 
a geological horizon for field purposes; and an intermediate 
horizon has been used, consisting of layers of black oyster- 
shells, and called by the members of the corps “ the black 
shell-rock.” 

The Tezoatlan coal-field has been more closely examined 
than any of the others, and the following section of it may be 
regarded as typical: 


Downward Section of Tezoatlan Coal-Field. 


Cretaceous limestones, . 

Calcareous and arenaceous shales, including the 
“ black shell-rock,” . 

Upper coal-bearing shale, . 

Sandstones and conglomerates, .... 
Lower coal-bearing shales, .... 

Intrusive or archaic rocks. 


massive and of great thickness. 

about 500 ft. 

110 ft. 

800 ft. 

at least 800 ft. 


The upper coal-bearing shales have not been examined, 
except superficially, since the lower shales appeared to have 
greater value. Several sections have been made of various por¬ 
tions of the lower coal-bearing shales, which vary in thickness 
according to where they are cut off by the intrusive rock. The 
following is offered as representative: 


Section below the 800 Feet of Sandstones and Conglomerates Noted 

in Preceding Section. 


Sandstones, 

• • • • • 

Ft. 

6 

In. 

0 

Calcareous shale, 

• • • • • 

. 20 

0 

Sandstones, 

• • • • • 

4 

0 

Ferruginous, calcareous, 

and arenaceous shales, . 

. 48 

0 

Sandstone, . 

• • • • • 

o 

. . . o 

0 

Ferruginous and arenaceous shales, . 

. 19 

0 

Carboniferous shales, 

• • • • • 

3 

0 

Sandstone,. 

• • • • • 

3 

0 

Coal. Seam A, . 

• • • • • 

4 

0 

Shale parting, . 

• • • • • 

o 

• • • JU 

0 

Coal, .... 

• • • • • 

1 

0 

Blue shale, 

• • • • • 

• . . 7 

0 

Coal, .... 

• • • • • 

1 

0 


3 The Botanical Gazette, vol. xlviii., No. 6, p. 427, et seq. 

[14] 











EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


685 


Ft. In. 

Arenaceous and calcareous shales, . . . . . 33 0 

Coal , ............ 1 0 

Carboniferous shales, ........ 2 0 

Blue shales. .......... 8 0 

Arenaceous shales, ......... 8 0 

Coal, . .10 

Shale, ........... 3 0 

Coal. Seam B, .......... 5 6 

Shale, ........... 8 0 

Coal, ........... 1 0 

Shale, ........... 4 0 

Coal. Seam C, . . . . . . . . . . 2 0 

Shale parting, .......... 2 0 

Coal, ............ 0 6 

Arenaceous shales, ......... 14 0 

Coal, .4 0 

Shale, . ......... 10 0 

Coal, .2 0 

Calcareous shales, ......... 8 0 

Coal, ............ 2 6 

Arenaceous shales, ......... 4 6 

Sandstones, ........... (3 0 

Carboniferous shales, ......... 2 0 

Shales, ........... 40 0 

Coal. Seam I), . . . . . . . • • • 6 0 

Sandstones and shales, ........ 58 6 

Coal, ............ 2 0 

Sandstones and shales, ....... . 80 0 

Coal. Seam E, . . . . • . . • • • 5 0 

Sandstones and shales, ........ 121 6 

Coal. Seam F, . ....... 5 0 

Sandstones and shales, . . . . . • • .716 

Coal. Seam 70 

Sandstones and shales, ........ ? 

Coal, .0 10 

Shale,.2 8 

Coal, .0 10 

Shale,.2 8 

Upper split of coal seam No. 3, . . . . • • 5 10 

Shale parting,..25 

Coal parting,.0 8 

Shale parting,.0 7 

Lower split of coal-seam No. 3, .... 6 4 

Gray shale, .......... 8 3 

Coal, . .......... 0 6 

Iron shales, ..........HO 

Coal, ............ 0 5 

Shale, ...........10 

Coal, * ^ ^ 

Hard shales, .......... 8 3 

Coal. Seam 2, . . . . . . • • • . 12 0 

White shale and clay,.6 0 


[ 15 ] 










686 EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 





Ft. 

In. 

Coal. Seam 1, . 



5 

0 

White clay, .... 

• • • 

• • • 

3 

0 

CW, ...... 



0 

6 

White and iron-shales of varying 

thickness down 

to intrusive rock. 




This section shows a total of 83 ft. 2 in. of coal, in which 15 
seams over 2 ft. in thickness aggregate 72 ft. 8 in., and 9 of 
these, exceeding 3 ft., give an aggregate thickness of 64 ft. 
8 in. 

The intrusive rocks cut these formations at various points, 
but, in the coal-lields proper, the nearest they come to the coal- 
seams is (excepting one or two places) about 100 ft. below 
coal-seam K. Coal-seam K is not designated in the section. 
On account of the undetermined rocks below seam K and above 
seam 3, the nomenclature of the seams was changed at this 
point. 

The formations are faulted and folded, but not so much as 
would be expected. The dip is generally between 30° and 50° 
west at Mina Consuelo, and the same amount to the east at the 
opposite side of the basin. In places, the coal lies horizontal 
in small areas, while the faults, with the exception of quite a 
large one on practically the axis of the synclinal (where there 
has been a displacement of nearly 1,000 ft.), are unusually small, 
although numerous. Three faults have been found, of 200, 
120, and 55 ft. displacement, respectively, while there are many 
others which vary from a few tenths of an inch to a foot or 
more. The general strike in the vicinity of Consuelo is H.-S., 
but in approaching the town of San Juan Diquillu it swings 
around to E.-W. 

Coal-Fields and Character of Coal. 

The field-headquarters were located in Tlaxiaco, which, 
although more than 80 miles by horse-trail from the nearest 
railroad-station, has a population of 8,000, a small water-supply, 
electric light, and a large number of stores. The relative loca¬ 
tions of the various fields will be referred to this place. 

In the Penasco field, 10 miles SE. of Tlaxiaco, a high-grade 
coal in small deposits was found by an exploring-party. A 
sample from the Junuzma mine gave, upon analysis, moisture, 
9.45; volatile matter, 25.85; fixed carbon, 60.45; and ash, 
4.25 per cent. 


[ 16 ] 




EXPLORATION OF IRON-ORE AND COAL-DEPOSITS 


687 


HOLE No.4 


'ft I 

0 H 
rt.P S 

03 ft' £■ 

T) 

OO 

p 

03 

« ST 

0 

c* 

0 H ^ 
Cr m 
03 o' % 
t7 Pfft 

0 e 

(T? P 

“er-O 

5 « 0 

3-. o*S. ‘ 

s~ 2 £ 

Q 

s 5 2. 

r* « (J 

-! r* 

w ^ 

00 

0 ^ 

0 


M P 

5* £ 5 - 

a 8 g. 
18 01 , M 

6 cr 

w ^ 

CO 

g « ? 

Ct> 


iasN 


Surface of Ground 


Surface 



40 r 4 

4l'() i0 -® 
41'10' 
42'8* 
43 / 6- 
43'11 
l 4G'_2“ 
47'.21 
48'P" 
48V 


53'2'1 


105'2 


108'G 
108'8 
109'2 

in': 


113'G 

114'G" 

115'0" 


123'0. 

124'10” 

.12G-1" 


129 V 
130V 

132'j 
133'0 

jCarb.Sha lcs 2^ 

Sand Shales 6" 
Carb.Shales 10” 

Coal 10” I . 

KW? I “°'°- 

ShaleSt3[ *o n 
Carb.Shales 1 0 
Slate 10 rr S 
Coal 5” § 

Black 



188'Ot; 

1894 



Slate 1*4 
Coal 4” 


M 
® 
t- o' 

^ CJ* 


Cr^ O 

Sandy Slate 
3'i" 

Carb.Shales 2” 
Coal 6" 

Slate 2'I ! 

Coal 2 / 3* ‘ 
Carb.Shales 
l'O’ 

Sandy Slate 6" 
Coal 2'1^ ^ 

Sandy 04 
Shales 
5'8” 



-- 


Coal l'10f" M g 

CP 

Shale 

JL '31 


C-4 

P> 

a 


C5-5- 


G9^G" 

G9 7 9” 


731 


83,81 


89'6" 


Shales 
4'9” 

I Coal 3'ld” 

ICarb.Sha i 
Sand 
Shales £ 
I'ft" T- 

10 *° a y 

Sandstone £ 
i'6" § 

Coal i'll" 
Slate Q| 

Carb.Shales 

Coal 3M l 

Carb. ^ S 
Shales ~ 

3^2” 

Slate 7'2f' 


Fine 
Sandstone ^ 

v> /l ft 7 o 

r iu o o 

Coarse 

Sandstone” 

3'0' 


.117'8 


151'7 
152'8- 
154'4- 
155'4 
15G'4' 
158' 


lG2i 


165'V 

IGII'7" 

lG7 r 

1G7' 

1G9_(_ 

I7l'2l 


177'10- 

18l'V 

181'i 

183 ^8 


Coal 3'5* 
Shale 8* 
Coal 2'2 
Slate 8 ' 
Coal 2'2‘ 

Slate l'l0 


Fine Sand c-c 
and I § 
Blue Shales l. 


4'4" 

„ ^ o 

Brown v \ g 



Slate 
3'4” 

Coal 311 

Sis- 

o 

, to 
Shale 11 h 

CoaH'8'| § 

Carb.Shales 
l'O'' I 
Blue Slate 
l'O” I 
Coal l'lO ' 

Shales 1'2” 

I Coal 3'4 
Shale 11 


c - 


I Coal g" 
Shale 7' 
Coal I'll!" 
Shale 1'7' 

1 Coal 1'9 


KSSa- 


Slate 2" 
Coal 1'3 

Carb.Shales 


Fine 

IV y Sandstone9c 
Shale FTS * - 
Carb.Shales 2 18b -£ 
Slate 2'07’» 


(Shale 7"t 
Coal 2 'l 


Shales i'i' r 


O 

■S 


*■3 

a 

o o' 


Carb. 

Shales c § 9“ 
l'G" 

Conglomerate 

rf 

4 1 o' 


Depth 

Below 

Surface 

m 
> 
03 


> 

o 

m 

o 

■u 

03 

X 

> 

T] 

H 


5'1” 


Slate 

2'8“ r 

Coal i'r « 
Slate 4” l 
Sandstone 
1 ' 8 * 


220 0 



Hole Discontinued 


03 

O 

c 

H 

I 

-n 

> 

o 

m 

o 

n 

03 

X 

> 

*T1 

H 


Character 

and 

Thickness 
^ of Strata 

rn 

03 

H 

T1 

> 

o 

o 

T1 

03 

X 

> 

“n 

H 

Wash 


l H 

25 0 



Lime Shale 


sV' 


-Dirty Coal 9 

/ // 

Coal 2 7 


Dirty Coal 2 10 


Lime Shale 1 10 ' 


Coai 1-9 


t n 

1 9 


Lime Shale 

Coal l-o" 

- / // 

Lime Shale 1 1 


Carb. Shale 2 V' 


* / H 

Coal 11 




Lime Shale 7 4 




/ // 

96 0 


/ // 

100 0 


nm 

w«m 

N-.v^y-xv^x 


Carb. Shale 


t n 

3 1 


Carboniferous 

t <f 

Sandstone 14-9 



Fig. 4.—Record of Diamond-Drill¬ 
ing at Mina Consuelo, Oaxaca, 
Mexico. 


Fig. 5.—Section of Shaft A on an 
East and West Line, Mina Con¬ 
suelo, Oaxaca, Mexico. 


[ 17 ] 

















































































































688 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


The Tepejilla field, about 20 miles N\\ r . of Tlaxiaco, covers 
a small area; and the coal found there is high in ash and appa¬ 
rently small in quantity. 

The Juxtlahuaca field includes outcrops in the vicinity of the 
towns of Juxtlahuaca and Silacayoapam, where preliminary 
investigation showed the coal to be non-coking and high in ash. 
Samples showed on analysis the following results: 



Juxtlahuaca. Silacayoapam. 


Per Cent. 

Per Cent. 

Moisture, \ 

5 9 

9.27 

• • • 

Volatile matter, > 

• Vt 1/ 

27.36 

Fixed carbon, .... 

42.0 

39.93 

Ash, ...... 

52.1 

23.44 

Analyzed by 

0. I. & C. Co. 

Instituto Geologico. 

The Tecomatlan field, embracing the outcrops in the vicinity 

of Tecomatlan, in the State of Puebla, and 

Santa Ana Pay on. 

Oaxaca, is 75 miles N¥. of Tlaxiaco. The coal here is soft 

and pulverulent and showed on 

analysis: 



Per Cent. 

Per Cent. 

Moisture, ..... 

1.8 

2.0 

Volatile matter, .... 

17.1 

18.3 

Fixed carbon, .... 

57.1 

48.7 

Ash, ...... 

% 

24.0 

31.0 


The Tlaxiaco field, the Mixtepec field, 12 miles W. of Tlax¬ 
iaco, and the Tezoatlan field, 25 to 30 miles NW. of Tlaxiaco, 
are those in which most development-work has been done, and 
will be described in detail under separate headings. 

In addition to the above localities, coal is reported as occur¬ 
ring in four or five other places; but samples showed it to be 
of inferior quality. 

Tlaxiaco Field. 

Since the company first acquired control of this field, its- 
work was started here, and was greatly facilitated by the pro¬ 
gressiveness of the people of Tlaxiaco, who, following the 
example of Sr. Salvador Bolanos Cacho, the Jefe Politico 
of the district, not only secured samples of iron-ore and coal 
from distant points, but aided us with their advice and in 
every possible way made our work pleasant and comfortable.. 
I take this opportunity of expressing my appreciation of the: 
uniform courtesy and kindness shown us by every one within 

[ 18 ] 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


689 


the boundaries of the State, from the Governor, Sr. Emilio 
Pimentel, down to the Presidente of the smallest town. 

The Tlaxiaco field was sub-divided into three tracts, the 
A illaverde, the Stein, and the Pio Tlaxiaco. The work done 
upon the Villaverde and Stein tracts consisted in mapping and 
uncovering some 14 outcrops and securing samples, which 
show the coal to vary greatly in composition, much of it 
appearing to he too poor for commercial use. Analysis from 
one of these coals gave the following results: 


Moisture, 
Volatile matter, 
Fixed carbon, . 
Ash, 


Per Cent. 
2.07 
16.77 
52.69 
28.47 


The work on the Rio Tlaxiaco tract consisted of eight drifts, 
which had a total length of 900 ft., including cross-cuts, and 
exposed seams varying from 10 in. to 6 ft. 0 in. in thickness. 
Most of these seams are very dirty and show the effects of con¬ 
siderable faulting, the seams consisting of flakes of coal and 


slate. 

The following 

o 

are the analy 

ses of 

some of the 

better 

seams 

• 

• 





Seam 

Thickness 

Moisture. 

Volatile 

Fixed 

Ash. 

Number 

of Seam. 

Matter. 

Carbon. 


Feet. 

Per Cent. 

Per Cent. 

Per Cent. Per Cent. 

4 

2 

1.8 

18.1 

42.1 

38.0 

4-A 

3 

0.7 

15.1 

46.0 

38.2 

5 

4 

6.6 

19.2 

29.7 

44.5 

6 

6 

1.6 

16.4 

53.0 

29.0 


Mixtepec Field. 

Upon the discovery of better coal at Mixtepec, the work was 
transferred to this locality and a large number of drifts were 
driven, the longest being over 1,100 ft., which showed that 
the seam was 25 ft. thick and extended over a large area. 
Numerous samples were taken, an average of the seam show¬ 
ing : 

O 


Per Cent. 

Moisture, .......... 1-3 

Volatile matter,. . . . • • • • • 16.2 

Fixed carbon, .... ..... 67.5 


[ 19 ] 



690 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


Besides this seam, known as the Esperanza, there are three 
others, designated as Fabrica, Soledad, and Southern. The 
Fabrica seam, 6 ft. thick, gave: 


Per Cent. 

Moisture, ......... 1*24 

Volatile matter, . . . . . • • • 16.21 

Fixed carbon, . ... ..... 60.23 

Ash, .......... 22.32 

The Soledad seam, 5 ft. thick, showed : 

Per Cent. 

Moisture, ......... 1.06 

Volatile matter, . . . . . . . • 14.03 

Fixed carbon, ......... 66.69 

Ash,.16.22 

The Southern seam, 3 ft. thick, gave: 

Per Cent. 

Moisture, . . . . . . . . . 13.69 

Volatile matter, ........ 28.78 

Fixed carbon, ......... 25.38 


The Southern seam, which appears to be rather a lignite than 
a true coal, is located about 4 miles from the Mixtepec field 
proper. 

All of the above analyses represent the “ run-of-mine,” the 
large pieces of slate only being removed. As the Mixtepec 
coal is quite soft, some crude tests showed that the ash could 
be reduced to one-half the original content by sizing on revolv¬ 
ing screens, while washing or jigging would make a still 
greater reduction. 

As the percentages of ash appeared high, two samples were 
taken and tested in a calorimeter to determine their fuel-value. 
The dirty coal, carrying 29.38 per cent, of ash, yielded 11,400 
B.t.u., while a clean picked sample, containing 3.85 per 
cent, of ash, gave 15,900 B.t.u. 

As the evidence of the value of the coal-fields appeared to 
increase greatly upon examination, it was decided to purchase 
a diamond-drill; and, the nearest point to the railroad being 
the Tezoatlan field, the drill was sent there. Later a second 
drill was erected at the same place, and the entire force was 
moved to Mina Consuelo. 


[ 20 ] 











EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


691 


Tezoatlan Field. 

For the past 18 months all the development-work of the 
company has been confined to the Tezoatlan field, and here 
the work has reached its highest development, although still in 
progress. Some 35 drifts have been driven into the coal in 
order to show the continuity of the coal-seams along the out¬ 
crop, while seven diamond-drill holes and a shaft have been 
sunk to determine its extent in depth. More than 71 sq. miles 
have been covered by a geological survey; and the data thus 
collected have been mapped, while detailed geological and 
topographical surveys have been completed on 350 acres, and 
are now in progress on 1,000 additional acres. 

As shown in the geological section, the coal-seams 3 ft. or 
more thick in this locality have a total true thickness of 64 ft. 
2 in., although in part of the field the intrusive rocks have cut 
out the lower 29 ft. 2 in. of the seams, leaving available 35 ft. 
of coal. As the average dip is 30° or more, these true thick¬ 
nesses will be equivalent to vertical thicknesses of 74 and 42 
ft., respectively, and would yield, according to the rule of thumb 
(that 1 ft. vertical thickness gives a yield of 1,200 tons of coal 
per acre), 88,800 and 50,400 tons per acre, respectively. The 
upper 35 ft. of coal has been traced over an area of 3,000 
acres, while the total thickness of 64 ft. has been traced for a 
distance of 1.25 miles, though the work has not yet reached a 
stage permitting the determination of the area underlain by 
the total thickness of seams. The coal may be called an an¬ 
thracite, being hard and dense and burning without smoke, 
a typical analysis showing : 

Per Cent. 


Moisture, . . ......... 1.0 

Volatile matter, . . . . . . . . . .5.5 

Fixed carbon, . . . . . . . . . .73.5 

Ash,.20.0 

Sulphur, ........... 0.06 


11,500 B.t.u. 

This analysis represents the coal when mined and picked; 
the “ run-of-mine,” unpicked, carrying about 25 per cent, 
of ash. 

The Tezoatlan coal-field is a large basin, extending in a gen¬ 
eral N-S. direction, the distance between the eastern and west- 

[ 21 ] 











692 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


ern outcrops being, near the southern end, about 2 miles, 
while, on the north, the western outcrop is hidden by the Cre¬ 
taceous limestones, which are unconformable to the lower 
strata. 

An interesting feature of this coal-field is, that the intrusive 
rocks, which are considered to be Tertiary, have had practically 
no effect on the coals. In some places, coal-seams are found 
occurring with surprising uniformity within 20 ft. of the intru¬ 
sive rocks. The formations of the various strata in this vicinity 
are extremely interesting; and the rapid alteration of the 
strata (consisting of coal, shale, fine and coarse sandstones) 
shows that there was a constant variation of the depth of 
water during deposition. 

Iron-Ore. 

Although the preliminary reconnoissance in 1906 had for its 
object the investigation of certain deposits of iron-ore, with the 
idea of utilizing them in the manufacture of iron, using either 
charcoal or imported coke as fuel, the coal-deposits appeared to 
be of more immediate value than those of iron-ore ; and there¬ 
fore nearly all the work has been done on the fuel-deposits. 

There is no doubt that a waiting market exists for iron- and 
steel-products in Mexico, as these now command high prices on 
account of freight charges and import duties. Pig-iron sells 
for $40 per ton in Mexico City, castings at $50 per ton and 
upward; and the duty on pig-iron is $5 per ton, while that on 
certain finished products is as high as $150 per ton. 

The iron-ores in the State of Oaxaca are of high grade. 
Thirty-three samples, taken from within an area of 4 sq. miles 
and tested in the field-laboratory, showed an average of 60.87 
per cent, of metallic iron. George C. Davis, chemist, of Phila¬ 
delphia, made an analysis of a sample, closely representing the 
average of the Cahuacua ore, which showed Fe, 65.86 ; S, 0.06; 
and P, 0.03 per cent. The phosphorus and sulphur are low in 
all the iron-ores of this district, and in the deposit which has 
been most largely developed there are indications of large quan¬ 
tities of high-grade Bessemer ore. Samples from a deposit at 
El Carnero averaged 66 per cent, of metallic iron, and Mr. Davis 
made an analysis of a hand-sample, with the result: Fe, 63.20; 
Si0 2 , 8.25; P, 0.024; and S, 0.03 per cent. In the locality 
known as La Ferreria, the average iron-content of the ore, 

[ 22 ] 


EXPLORATION OF IRON-ORE AND COAL-DEPOSITS. 


693 


as determined in the company’s laboratory, was 66.02 per 
cent.; and an analysis by Mr. Davis from a different sample 
showed Fe, 68.93; Si0 2 , 2.80; P, 0.026 per cent. In the vi¬ 
cinity of Tlaxiaco iron-ores were found containing Fe, 51.71; 
Si0 2 , 4.61; P, 0.026 per cent. Some iron-ore deposits exam¬ 
ined in the State of Puebla gave Fe, from 42.40 to 67.0; SiO,, 
from 1.30 to 15; CaO, from a trace to 8.80; P, from 0.004 to 
0.051, and S, from 0.01 to 0.15 per cent. 

These analyses are offered to show that ores collected from 
deposits scattered over a large area are rich in iron and low in 
sulphur and phosphorus. A few months’ work at the Cahua- 
cua deposit disclosed about 4,000,000 tons of iron-ore. The 
El Carnero ore is mainly magnetite; that of Cahuacua, mixed 
magnetite and hematite; that of La Ferreria, hematite and 
limonite; and that near Tlaxiaco, limonite. In the State of 
Puebla, the iron-ores are limonite and magnetite. 

Transportation. 

The extent of the exploratory work herein described was 
deemed essential by reason of the location of the coal-deposits 
as related to existing transportation-facilities. The railroads 
of Mexico, which now aggregate 14,000 miles, have in but few 
instances penetrated the mountainous section, and no existing 
line is nearer than 80 miles to the coal-fields. But, coal and 
iron-ores having been found in sufficient quantity to warrant 
the construction of railroad communications, reconnoissances of 
several railroad-routes have been made, which need not be dis¬ 
cussed at this time. Notwithstanding the mountainous country 
traversed, practical routes were found, which would connect 
the present railway-system of Mexico with the coal- and iron- 
ore deposits of Oaxaca, and might be extended to the Pacific 
coast, with moderate curves and grades not exceeding 2 per 
cent.; the estimated construction-cost being moderate for the 
character of the territory traversed. 


I 




MAY 3 I a i f 


i 


























































